1. Field of the Invention
This invention pertains in general to the manufacture of semiconductive products, and more particularly, to a method and system for determining the best integral process path to process semiconductor products.
2. Description of the Related Art
In a semiconductor manufacturing process, semiconductor wafers are patterned and processed to produce integrated circuits (ICs). To produce an IC, a specific manufacturing process is provided to define a sequence of operations in the manufacturing process based on the requirement of the IC. Taking a manufacturing process of 16-Mbit dynamic memory IC as an example, the operations comprise at least a photolithography operation, an ion-implanting operation, and a resist-removed operation. There is at least one tool in each operation and the tool is chosen randomly to carry out the manufacturing process, and the number of acceptable ICs produced in the manufacturing process is termed “yield.”
Controlling a manufacturing yield is an important issue in the production of semiconductor products, which can be wafers or chips and the respective yield is termed “wafer yield” and “chip yield.” Generally, a manufacturing yield indicates the efficiency and cost of production lines in a semiconductor fab. When the yield is increased and the stability of the yield is controlled, the fab generally is able to maintain a steady production.
To improve the yield of semiconductor products, an integration engineer is generally asked to optimize all of the tools of a particular operation to that of the best performing tool. The integration engineer generally relies only on his/her experience in the optimization process. However, this process addresses a single operation at a time and ignores the relationship between operations and between tools within the same operation. Therefore, this method does not consider an overall process integration. During a manufacturing process, semiconductor wafers are processed through a process path that includes a sequence of operations using various manufacturing tools. Because there are numerous possible integral path combinations, it is impossible to determine the best path by means of the above-mentioned conventional method.